Combination of organic mercury compounds and 1, 2-propylene-bis-dithiocarbamic acid salts as fungicides for rice plants



United States Patent 3,342,670 COMBINATION or ORGANICMERCURY coM- POUNDS AND 1,2-PROPYLENE Bis DITHIO- CARBAMIC ACID SALTS As FUNGICIDES FOR RICE PLANTS Herbert Ferdinand Jung, Tokyo, Japan, and Hans Schein- The present invention concerns a novel combination of active agents consisting of known fungicidal mercury compounds and known salts of 1,Z-prOpylene biS-dithiocarbamic acid and exhibiting a particularly favorable fungicidal activity.

The use of fungicidal organic mercury compounds in rice cultivation, particularly for the control of Piricularia oryzae, has already been disclosed. However, disadvantages are experienced during this process due to the high toxicity of the mercury compounds towards warm-blooded creatures and due to their phytotoxicity. It is necessary to keep the dosages as low as possible. Organic mercury compounds, for instance phenyl mercuric acetate, also havea phytotoxic activity towards certain varieties of rice and they cannot therefore be employed on all varieties of rice at the concentration required for elfectiveness. It is alsoknown that organic mercury compounds largely develop a curative (chemotherapeutic) activity. Their protective activity is relatively weak. In addition, the fungicidal organic mercury compounds are not effective against all diseases encountered in rice cultivation. Thus, they do not for instance develop a suflicient effect against Corticiumsasakii. t

It has also been disclosed that salts of 1,2-propylenebis-dithiocarbamic acid can be employed as fungicides. However, until now nothing has been disclosed about the activities of these substances during the control of fungus diseases on rice. I Itis an object of the present invention to provide novel synergistic combinations of active agents which have fungicidal properties and are particularly suitable for the control of diseases on rice. A further object consists in the indication of those fungicidal agents which only exhibit a low toxicity towards mammals. Other objects are evident from the following description and from the example.

It has been found that novel combinations of active agents from (1) fungicidal organic mercury compounds and (2) salts of 1,Z-pIopylene-bis-dithiocarbamic acid exhibit a particularly good activity during the control of V fungus diseases on rice.

The fact that no decrease in the curative activity takes place among the fungicidal mercury compounds while at the same time an increase in their protective activity is experienced when a part of the mercury compounds is replaced by salts of 1,2-propylene-bis-dithiocarbamic acid \must be regarded as distinctly surprising.

The combintions of active agents according to the invention exhibit various advantages. Thus, their toxicity towards warm-blooded creatures and their phytoxicity is only relatively slight. Moreover, the spectrum of the diseases on rice which can at the same time be controlled by them is widened. The combinations of active agents exhibit a high protective activity and a curative effect at the same time.

The term fungicidal organic mercury compounds refers to the known lmercury compoundswhich are employed for the control of fungus diseases. For the combination according to the invention, particular consideration may be given to organic mercury compounds of the general Formula I:

wherein R represents aryl such as phenyl, alkylaryl such as methylphenyl, halogenoaryl such as chlorophenyl, a hetero cyclic radical such as pyridine, or alkyl with 1 to 6 carbon atoms, and

X represents an inorganic acid radical such as halide, particularly iodide and chloride, or half an equivalent of sulphate, and organic acid radicals such as acetyl and sulphenic acid radicals.

The following may be mentioned in detail as examples of organic mercury compounds: phenyl mercuric acetate, phenyl mercuric iodide and phenyl mercuric chloride.

The term salts, of 1,2-propylene-bis-dithiocarbamic acid quite generally refers to the salts of this bis-dithiocarbamic acid with a known fungicidal activity. The zinc, manganese and nickel salts are particularly suitable. Mixed salts, for instance the manganese zinc mixed salt, also have a special activity. In this connection, the content of zinc 1,2-propylene-bis-dithiocarbamate may vary between 20 and The proportions of the two groups of active agents in the mixture may be varied within wide limits. In general, the combination of the active agents may contain between 5 and 99 percent by weight, preferably between 80 and percent by weight, of the bis-dithiocarbamate salt.

The combinations of active agents according to the invention exhibit a strong fungicidal activity on fungus diseases encountered in rice cultivation while their toxicity towards warm-blooded creatures is low. The effects develop rapidly and last for a long time. The combinations of active agents are for instance active towards Piricularia Oryzwe and Cochliobolus m'z'yabeanus and Corticium sasakii.

The combinations according to the invention may be applied by themselves or in the form of the usual compositions, such as emulsifiable concentrates, spray powders, pastes, soluble powders, dusting agents and granulates. These are prepared in known manner [cf., Agricultural Chemicals, March 1960, pages 35-38). The following may be mainly considered for use as assistants for this purpose: solvents such as aromatic hydrocarbons (for instance xylene-, chlorinated aromatic hydrocarbons (for instance chlorobenzenes), parafiins (for instance petroleum fractions), alcohols (for instance methanol), amines (for instance ethanolamine) and water; carriers such as natural ground uninerals (for instance kaolines, chalk) and synthetic ground minerals (for instance highly dispersed silicic acid); emulsifying agents such as non-ionic and anionic emulsifying agents (for instance polyethylene oxide esters of fatty acids, alkyl sulphonates); and dis- Patentecl Sept. 19, 1967 persing agents such as lignin, spent sulphite liquors and methylcellulose.

The active agents according to the invention may be present in the compositions in the form of mixtures with other known active agents.

In general, the compositions contain between 0.1 and 95 percent by weight of the active agent, and preferably between 0.5 and 90 percent by weight.

The combinations of active agents according to the invention are applied by themselves or in the form of their compositions by the usual methods, for instance by spraying, sprinkling or dusting.

The following example is given for the purpose of illustrating the invention.

Exam ple Field test with Pirz'cularia oryzae on water rice (Oryza swtiva jap'onica), Type Norin 21.

The active agents are applied in the form of their aqueous suspensions. When mixtures of active agents are employed, aqueous suspensions of the individual active agents are first prepared'separately. The suspensions are subsequently mixed. The preparation of the suspensions is carried out by the normal method with the use of an emulsifying agent.

Water rice is planted on plots of an area of 3.5 square meters. The plots are subjected to natural infection. The first treatment is carried out 14 days after planting, by sprinkling the plants with the suspension of the active agents. It is applied at the rate of 1,200 liters per hectare. A second treatment is carried out '14 days after the first treatment, by the same method. The evaluation is effected four weeks after the second treatment, 200 leaves from each plot being employed for an estimation of the degree of infestation. The degree of infestation expresses the infestation on the experimental plot as a percentage of the maximum possible infestation. From this result, it is possible to calculate the degree of activity, which specifies the percentage reduction of infestation compared with the untreated plot. The degree of activity may vary between and 100, where 0 indicates that the infestation was just as high-as for the untreated control and 100 indicates that an infestation has been prevented altogether.

The following table specifies the active agents, the contents of the active agents in the suspensions as well as the degree of infestation and the degree of activity. The stated data represent average readings from three repeated determinations.

It is evident from the following table that when the concentration of the active agent is 0.05% and also when the concentration of the active agent is 0.025%, Zinc 1,2-propylene-bis-dithiocarbamate only has a low degree of activity. When phenyl lmercuric acetate is applied at a 0.0043% concentration of the active agent, the achieved degree of activity is satisfactory for practical purposes. However, a considerable disadvanatge of mercury compounds consists in the fact'that they exhibit a high toxicity towards warm-blood creatures. An effort is therefore always made to keep the concentration of the active agent as low as possible in the case of mercury compounds. However, when compositions of the active agent with a content of 0.00215 of this active agent are employed, the degree of activity is already reduced to 44. This degree of activity is too low for practical purposes.

When use is made of a combination of active agents according to the invention, which for instance contains 0.025% of zinc 1,2-propylene-bis-dithiocarbamate and 0.0021.5% of phenyl mercuric acetate, the achieved degree of activity (74) is practically as high as the degree of activity (77) attained at a 0.0043% content of active agent with the mercury compound although only half the required amount of the mercury compound (degree of activity 44) has been applied in conjunction with a very small amount of zinc 1,2-propylene-bis-dithiocarbamate,

which on its own only exhibits a very low degree of activity (2). The degree of activity is a measure for the practical value of an active agent since it indicates both the protective and curative effects. The combinations of active agents according to the invention clearly exhibit a synergistic effect.

TABLE Content Degree of Degree of of active infestation activity Active agents agent, as on experiof the percent mental products plots Zinc 1,2-propylene-bis-dithio- 0.05 39. 0 15 carbamate. 0. 025 44. 9 2 Nickel 1,2-propylene bis-dithio- 0.05 38. 1 17 carbamate. 0. 025 46. 2 O Zine/manganese 1,2-propylene- 0. 05 39. 4 14 bis-dithiocarbamate (1:1). 0.025 44.9 2 Phenyl mercuric acetate g 11 Zinc 1,2-propylene-bis-dithio- 0 095 carbamate-l-phenyl mercuric 6, i1. 9 74 acetate. Nickel l.2-prip3illenc-lbis-dithio 0 025 14 7 68 czubamate p any mercuric momma +0. 00215 Zinc/manganese 1,2-pr0pylenc- 0 025 bis-dithiocarbamate 1;1 00,15 13.3 71 phenyl mercuric acetate. Untreated control 45. 8 0

We claim:

1. A method for controlling fungus diseases in rice which comprises contacting the plants with a fungicidal composition containing as active ingredients (1 a compound of the formula wherein R is a member selected from the group consisting of phenyl, methylphenyl, chlorophenyl and alkyl of 1-6 carbon atoms; and X is a member selected from the group consisting of an inorganic acid radical, acetyl and sulphenic acid radicals; and (2) a member selected from the group consisting of zinc and nickel salts of 1,2-propylene-bis-dithiocarbamic acid and a Zinc/manganese mixed salt of 1,2- propylene-bis-dithiocarbamic acid; the percent by weight ofcomposition of ('1) and (2) being about .002% and .025%. 2. A fungicidal composition containing as active fungicides (1) a compound of the formula wherein R is a member selected from the group consisting of phenyl, methylphenyl, chlorophenyl and alkyl of 1-6 carbon atoms; and X is a member selected from the group consisting of an inorganic acid radical, acetyl and sulphenic acid radicals; and (2) a member selected from the group consisting of zinc and nickel salts of 1,2-propylene-bis-dithiocarbamic acid and a zinc/manganese mixed salt of 1,2- propylene-bis-dithiocarbamic acid; the percent by weight of composition of (1) and (2) being about .002% and 025%. 3. The method of claim 1 wherein (1) is phenyl mercuric acetate and (2) is the zinc salt of 1,2-propylene-bis-dithiocarbamate. 4. The method of claim 1 wherein (1) is phenyl mercuric acetate and (2) is the nickel salt of 1,2-propylene-bis-dithiocarbamate. 5. The method of claim 1 wherein (1) is phenyl mercuric acetate and 2) is a zinc/manganese mixed salt of 1,2-propy1enebis-dithiocarbamate.

6. The composition of claim 2 wherein (1) is phenyl mercuric acetate and (2) is zinc 1,2-propy1ene-bisdithiocarbamate.

7. The composition of claim 2 wherein (1) is phenyl mercuric acetate and (2) is nicke-l 1,2-propylene-bis-dithiocarbamate.

8. The composition of claim 2 wherein 10 (1) is phenyl mercuric acetate and (2) is a zinc/manganese mixed salt of 1,2-propylenebis-dithiocarbamate.

6 References Cited UNITED STATES PATENTS 12/1933 Kharasch 167-38 4/1962 Zeile et a1 167-13 5/1963 Pugh 167-30 X FOREIGN PATENTS 3/ 1962 Germany. 1 1/ 1963 Germany.

7/ 1960 Great Britain.

ALBERT T. MEYERS, Primary Examiner. J. S. LEVITT, S. ROSEN, Examiners. V. C. CLARKE, Assistant Examiner. 

1. A METHOD FOR CONTROLLING FUNGUS DISEASES IN RICE WHICH COMPRISES CONTACTING THE PLANTS WITH A FUNGICIDAL COMPOSITION CONTAINING AS ACTIVE INGREDIENTS (1) A COMPOUND OF THE FORMULA 